Ultrafine particles (UFPs) are a subset of fine particles, typically defined as those smaller than 100 nanometers. Despite their abundance in urban air, especially from sources like traffic and residential heating, they carry very little mass. As a result, they’re nearly invisible to traditional mass-based monitoring methods, which remain the basis of air quality regulations in many parts of the world.
Why Measure UFPs?
Their tiny size makes UFPs behave differently than larger particles in both the atmosphere and the human body. These particles can penetrate deep into the lungs and even enter the bloodstream, posing serious health risks. From a scientific perspective, understanding UFPs also provides crucial insights into atmospheric processes, particle evolution, and climate impacts.
How Are UFPs Measured?
Because UFPs contribute little to mass, they are best quantified using number-based measurement techniques - counting each particle in a given volume of air. This approach captures what mass-based methods miss.
For deeper analysis, measuring not just how many particles are present, but also how large they are, helps build a full picture of particle behavior and origins. This is done through particle sizing instruments that determine Particle Number Concentration (PNC) and Particle Size Distribution (PSD).
To ensure accurate results, UFP measurements must begin with proper air sampling—ensuring that what reaches the instrument reflects what’s truly present in the environment.
Learn more about how UFPs are measured, why it matters, and the techniques used to capture their presence in the air.